This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | -1 |
| 5 | -10 |
| 6 | -65 |
| 7 | -350 |
| 8 | -1666 |
| 9 | -6510 |
| 10 | -7855 |
| 11 | 270050 |
| 12 | 4948669 |
| 13 | 63503440 |
| 14 | 702095030 |
| 15 | 6924754200 |
| 16 | 58870214129 |
| 17 | 356043924590 |
| 18 | -615569993285 |
| 19 | -74306502570650 |
| 20 | -1783956267419536 |
| 21 | -32695418069393310 |
| 22 | -520090808927130925 |
| 23 | -7317310078355307250 |
| 24 | -87056749651694635451 |